Weather and Traffic

The idea that near-normal sea surface temperatures in the tropical Pacific Ocean — a condition that’s become known as “La Nada” — leads to normal weather patterns in North America is incorrect, a climatologist with NASA’s Jet Propulsion Laboratory in Pasadena, Calif. says.

There is a tendency to assume that neutral conditions in the Pacific would lead to average temperatures in North America, but that hasn’t happened during the winter of 2012-2013 — at least in South Florida. For the most part, the current winter has been much warmer than usual, reflecting new difficulties in long-range forecasting through spring and summer.

“This absence of El Nino and La Nina, termed ‘neutral’ by some, has left long-range climate forecasters adrift,” says Bill Patzert, a NASA climatologist. “Seasonal, long-range forecasting works best when signals like El Nino and La Nino are strong.”

Patzert says he never uses the word normal when discussing winter weather in the western U.S. (That hasn’t been the case in the East, either.)

“For instance, in the last 100 years, we’ve only had a total of six ‘normal’ years of rainfall in Los Angeles, meaning about 15 inches of rain per winter in downtown L.A. Historically, La Nadas have delivered both the wettest and driest winters on record. For long-range forecasters, La Nada is a teeth grinder.”

The Pacific “La Nada” is its 10th month. The latest forecast from the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center is for neutral conditions to continue through spring, and most computer forecast models indicate that the Pacific will remain in neutral through summer as well.

That’s likely to make this year’s hurricane forecast even more challenging. There are a lot of factors that go into a hurricane season forecast, including sea surface temperatures in the Atlantic and trade wind trends. But it’s worth noting that both 2003 and 2005 were neutral years, and both were unusually active — 2005 was the busiest hurricane season on record.

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Louis Uccellini will become the 16th director of the National Weather Service on Sunday. Acting Director Laura Furgione was named the agency’s deputy director.

Uccellini has been the Weather Service’s head of the National Centers for Environmental Prediction since 1999. He oversaw seven national agencies under NOAA, the parent agency to the NWS, including the National Hurricane Center in Miami.

A graduate of the University of Wisconsin in Madison, Uccellini launched his career at the Goddard Space Flight Center’s Laboratory for Atmospheres in 1978. He joined the NWS in 1989.